1. Field of the Invention
The disclosed invention relates to gas compressor pumps and gas vacuum pumps, and is particularly directed to a design which uses metal or composite diaphrams to either compress gas or provide a vacuum in an oil free environment.
2. Prior Art
Air compressors producing about 125 to 250 pounds per square inch (psi) pressure are common industrial equipment. Most of these compressors are designed with reciprocating pistons which must be lubricated with oil to operate. The result is that oil inevitably gets into the compressed air and there are many applications for which this is unacceptable. There are compressors that provide oil free compressed air. These compressors are designed with pistons, cylinders and rings that have special coatings such as teflon for lubricating the moving parts. These oil free air compressors have low life times due to the sliding parts which eventually wear away the special coatings. Another disadvantage of the piston type compressors is that they generate substantial noise. This is due to the relatively high speed at which they must operate to provide a certain volume of air.
Another method of obtaining compressed air is the use of diaphrams. For low air pressures, pumps have been designed using diaphrams formed of elastomeric materials such as rubber. U.S. Pat. No. 2,109,718 is an example of such an air compressor. At higher pressures these elastomeric diaphrams break down due to the high temperatures produced at high pressure.
Metal diaphrams have been proposed for certain uses, such as in U.S. Pat. No. 3, 036,526, which discloses a metal diaphram pump for liquids. U.S. Pat. No. 3,503,307 discloses the use of a metal diaphram for a pressure reducing valve. U.S. Pat. No. 3,508,471 applies a metal diaphram to a positive expulsion device and U.S. Pat. No. 3,036,526 uses a metal diaphram for pumping slurry. Other patents such as U.S. Pat. No. 4,136,603 disclose a particular diaphram assembly for use in highly corrosive applications. A key feature of metal or composite diaphrams is their ability to withstand high temperatures. Composite diaphrams are generally more flexible than metal diaphrams.